Sectors 20 and 21 will be replaced with newly exported data files starting April 2020. During the ingest the data files will be a disparate set of both the original and new files. Upon completion of the ingest the check boxes in the data holdings table on the MAST website will be replaced with 'v2'.
The reasons for this re-delivery include changes in how the data quality flags for stray and scattered light are set. It also includes a correction to the time and to the full-frame image (FFI) collateral pixels. For more information, see the 'Memo' listed next to the data release notes for DRN27 and DRN29 on the MAST website. These memos's include information on how one can tell the difference between new and old data files.